Chart's Value cannot be changed automatically

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ActiveChart.PlotArea.Select
ActiveChart.SeriesCollection(1).XValues = "='"& xxx &"'!R"& yyy &"C4:R"& zzz &"C4"

If I try to run the Macro, it comes out with this error msg :
Error '1004'
The XValues-Properties from the Series Objects cannot be fixed (sorry translated).

All the xxx,yyy and zzz's are variable and they work well normally. yyy usually start with a value of about 250 (row 250) and end with a zzz value of about 700 (row 700). the problem only surfaces when yyy has a value of 2 or 3 (row 2 or 3) and zzz with value less than 200.

How can I change this vba programm? this problem can only be solved manually.

thanks in advance